Carburetor idle system air bleed

ABSTRACT

The carburetor idle system air/fuel channel has an additional air bleed that is opened and closed by an electrically controlled valve that is initially opened upon engine shutdown to bleed the idle channel fuel signal, to terminate fuel flow, and subsequently closed in response to engine vacuum decay, to recondition the idle channel for normal operation.

c I United States Patent 1191 1111 3,741,188 Rickey June 26, 1973 [54]CARBURETOR IDLE SYSTEM AIR BLEED I 2,817,325 12/1957 Meissner 123/198 DC3,482,562 12/1969 Ranft 123/198 DC [751 Invent R118" Rickey, DearbmnMlch- 3,682,148 8/1972 Harrison et al 123/198 DB x 73 A I F d 2,943,6157/1960 Kainz 123/198 DC x Sslgnee Motor Company Dearbom 3,354,87711/1967 Zub et a1. 123/1310. 11 3,158,144 1l/1964 Wacker 123/198 DC [22]Filed: Dec. 3, 1971 21 A L N 204 616 Primary Examiner Al Lawrence Smith1 pp 0 Attorney- Keith L. Zerschling and Robert E. Mc-

Collum [52] US. Cl. 123/198 DB, 123/D1G. 11, 123/119,

123/179 G [51] Int. Cl. F02m 19/12, F02m 1/14, FOZd 33/00 [57] ABSTRACT[58] Field of Search 123/010. 11,97 B, The carburetor idle systemair/fuel channel has an 123 93 1 193 DB, 193 DC, 79 B6, 179 G, ditionalair bleed that is opened and closed by an elec- 130 E tricallycontrolled valve that is initially opened upon engine shutdown to bleedthe idle channel fuel signal, [56] Refe n Ci d to terminate fuel flow,and subsequently closed in re- UNITED STATES PATENTS sponse to enginevacuum decay, to recondition the idle 3,577,966 5/1971 Collingwood123/198 DC x channel for normal operat'on' 3 Claims, 1 Drawing FigureCARBURETOR IDLE SYSTEM AIR BLEED This invention relates, in general, toa carburetor for an internal combustion engine. More particularly, itrelates to a carburetor constructed with apparatus to terminate the idlesystem fuel flow in response to engine shutdown conditions to preventafterrunning or dieseling of the engine.

Carburetor constructions are known in which valving is inserted in theengine idle system air/fuel mixture channel in response to engineshutdown to block off the flow of an air/fuel mixture to the enginecylinders to thereby prevent engine dieseling or afterrun. Such devices,however, generally are not satisfactory because of the extremely closetolerances required to assure that no fuel will leak past the valve whenit is closed, or that air will not leak into the idle channel around thevalve when the valve is withdrawn and normal operation of the idlesystem is desired.

It is an object of the invention, therefore, to provide an engineanti-dieseling device that automatically bleeds air into the engine idlesystem in response to engine shutdown to destroy the idle system fuelvacuum signal and thereby terminate fuel flow.

It is another object of the invention to provide a carburetorconstructed with an atmospheric air bleed that will admit air into aportion of the idle system channel upon engine shutdown to decay theidle system fuel vacuum signal so that flow of idle system fuel will beterminated, while subsequently automatically closing the air bleed portafter a predetermined time delay to recondition the idle system channelfor normal operation and conventional engine starting.

It is a still further object of the invention to provide a carburetorconstructed with an idle air/fuel channel having an air port that isnormally blocked by an electrically controlled valve operable inresponse to engine ignition shut off to open the air port and bleed thevacuum signal acting on the idle system fuel jet to thereby terminateidle system fuel flow; the valve control being de-energized after a timedelay corresponding to the time required for decay of manifold vacuumafter engine shutdown, to move the valve to close the air bleed port andpermit operation of the idle system in a conventional manner for enginestarting and running.

Other objects, features and advntages of the invention will become moreapparent upon reference to the succeeding detailed description thereof,and to the drawings illustrating a preferred embodiment thereof, whereinthe FIGURE illustrates schematically a cross sectional view of a portionof a carburetor embodying the invention.

The carburetor in this case is for the most part a conventional one ofthe downdraft type. It includes a valve body having a central boreconstituting the usual induction passage 14. The upper end of passage 14generally would be connected to an air cleaner assembly lel relationshipto induction passage 14 to supply an idle speed air/fuel mixture to theengine when throttle valve 18 is in its closed position shown. The upperend of the idle channel has a branch 24 connected to the air horn oressentially atmospheric pressure section of the carburetor through anorifice or anti-siphon bleed 26. The adjacent portion of passage 22contains an idle system fuel jet 28, the upstream end of which would beconnected to the conventional fuel float bowl, not shown. The top of thefuel in the float bowl normally is at the pressure of the top or airhorn section of the carburetor.

The lower portion of idle channel 22 contains the usual transfer port 34adapted to be straddled by the edge of throttle plate 18 when in itsclosed position shown. Also provided is an air/fuel mixture dischargeport 36, the area of which is controlled by an adjustable needle valve38.

Other details of construction and operation of the carburetor per se arenot given since they are known and believed to be unnecessary for anunderstanding of the invention. Suffice it to say, however, that innormal operation, when the engine is running, the vacuum sigso as to beopened to air essentially at atmospheric nal below the throttle valvewill act on discharge port 36 and that area of transfer port 34 locatedbelow the edge of the closed throttle valve. This will create a pressuredifferential across the two idle channel orifices 26 and 28, causing aflow of both fuel and air through the idle channel out into theinduction passage to the engine cylinders. This same vacuum signal,however, is present for a short-lived but determinate period upon engineshutdown prior to the engine crankshaft ceasing rotation, to continuedrawing an idle channel air/fuel mixture into the engine cylinders. Solong as this occurs, the engine may diesel or afterrun.

Turning now to the invention, therefore, the idle channel 22 is providedwith a branch passage 40 that is open to air at atmospheric pressure.The passage is adapted to be closed by a solenoid controlled valve thatis responsive both to engine ignition shutoff and a change in manifoldvacuum pressure.

More specifically, a hollow casing 42 is threadedly mounted in thecarburetor valve body as shown. It is open at opposite ends tocommunicate with air at atmospheric pressure at end 44 and with thepassage 40 at the opposite end 46. A valve member 48 is slidably mountedin shell 42 and aligned with passage 40 for movement to block or openthe passage. In this case, the valve is formed as an integral part ofthe armature 50 of a solenoid 51 having a coil illustrated at 52. Aspring 54 normally biases the valve to close passage port 40 when thesolenoid is de-energized.

The solenoid 51 is part of an electrical circuit that includes aconventional vehicle battery 56, an engine onoff ignition switch 58, anengine intake manifold vacuum controlled switch 60, and a relaycontrolled switch 62.

The vacuum switch may be of a known type having a spring 64 biasing thevalve to normally open the switch contacts 65 and break the circuit, andclosed to complete the circuit by intake manifold vacuum. The vacuum isconnected to switch 60 from a carburetor port 66 through a line 67.

The relay control switch 62 is closed by a spring 68 to complete thecircuit, when the relay is de-energized, the switch being opened tobreak the circuit upon energization of the relay coil 70.

It will be noted that the ignition on-off switch 58 and the manifoldvacuum control switch 60 are arranged in a parallel flow circuitrelationship between the battery and the relay control switch 62, andthat the latter switch is in a series arrangement with the solenoid 51.

In operation, with the engine off, no manifold vacuum will exist.Accordingly, vacuum switch 60 will be moved by spring 64 to unbridge thecontacts 65 and break the circuit between battery 56 and relay switch62. The latter switch will have been spring closed since coil 70 isde-energized by the open ignition switch 58. Therefore, solenoid 51 willbe ole-energized and spring 54 will maintain air bleed valve 48 seatedin the passage 40 to block the admission of additional air.

After the engine has been started, by closing of ignition switch 58,manifold vacuum will cause vacuum switch 60 to close and complete thecircuit from the battery 56 to the relay control switch 62. However,this latter switch will be in an open position due to the energizationof relay 60 by the completion of the circuit from battery 56'throughclosed ignition switch 58. Accordingly, no current flows to solenoid 51and the air bleed valve 48 remains seated. The engine idle systemair/fuel mixture flow, therefore, operates in a conventional manner, aspreviously described. The vacuum switch 60 and relay switch 62 willremain in the positions described for all operating conditions of theengine until such time as it is desired to shut down the engine.

Upon engine shutdown, the ignition switch 58 is opened to the positionshown, which breaks the circuit between the battery and the relaycontrol switch 62. This allows the latter switch to close and bridgethecircuit between the closed vacuum'switch 60 and solenoid At themoment of ignition shut off, the continuing rotation of the enginecrankshaft as it is slowing down continues to maintain a manifold vacuumon switch 60 to maintain it closed. Accordingly, for a predeterminedtime interval after engine ignition shut off, solenoid 51 will remainenergizedto open the air bleed valve 48 and admit atmospheric airpressure into idle channel 22. This will immediately decay the pressuredifferential across the fuel jet 28 to immediately terminate idlechannel fuel flow and thereby positively terminate con tinued running ofthe engine due to lack of a combustible mixture.

After a few seconds, the engine manifold vacuum will have decayed to apoint permitting the vacuum switch spring 64 to again open switch 60 andbreak the circuit between the battery 56 and solenoid 51. The air bleedvalve 48 then is closed by spring 54 and the idle channel again isconditioned for a-conventional operation for restarting and running theengine.

From the above, it will be seen that the invention provides an engineanti-dieseling device that is simple inconstruction and operation andyet positively terminates idle channel fuel flow after engine ignitionshut off to prevent continued running of the engine, while subsequentlyreconditioning the idle system for a normal operation. for enginestarting and running.

While the invention has been shown and described in its preferredembodiment, it will be clear to those skilled in the arts to which itpertains that many changes and modifications may be made thereto withoutdeparting from the scope of the invention.

-l claim:

1. An engine anti-dieseling control comprising, in combination, anengine carburetor having an induction passage open to atmosphericpressure at one end and adapted to be connected to an engine intakemanifold at the opposite end so as to be subject to engine vacuumvarying in level from ambient atmospheric pressure at engine shutdown toa maximum subatmospheric pressure level during engine decelerationoperating conditions, a throttle valve rotatably mounted across thepassage and movable from a closed position to an engine idle speedposition and beyond to a wide open throttle position, and return, forcontrolling flow through the passage, an idle fuel/air mixture channelconnected to the induction passage below the closed position of thethrottle valve so that the idle channel is subjected to manifold vacuumat all times to provide normal idle and off idle speed vacuum signalswith corresponding mixture flow, an air bleed port in the idle channel,an electrically controlled valve movable to open and close the port, anelectrical circuit including an electrical source and electricallyactuated means connected to the valve, first means responsive to engineshutdown completing the circuit and energizing the electrically actuatedmeans to move the valve to open the port and decay the idle system fuelvacuum signal to terminate idle system fuel flow to prevent enginedieseling, and second means responsive to engine shutdown subsequent tooperation of the first means to break the circuit and de-energize theelectrically actuated means to effect movement of the valve to close theport, the first means including a spring closed first switch in thecircuit and a relay associated therewith energizable to open the switchand break the circuit, and an engine ignition on-off second switch in'aseries circuit arrangement with the first switch between the source andswitch and in a parallel circuit arrangement with the second means.

2. An engine anti-dieseling control comprising, in combination, anengine carburetor having an induction passage open to atmosphericpressure at one'end and adapted to be connected to an engine intakemanifold at the opposite end so as to be subject to engine vacuumvarying in level from ambient atmospheric pressure at engine shutdown toa maximum subatmospheric pressure level during engine decelerationoperating conditions, a throttle valve rotatably mounted across thepassage and movable from a closed position to an engine idle speedposition and beyond to a wide open throttle position, and return, forcontrolling flow through the passage, an idle fuel/air mixture channelconnected to the induction passage below the closed position of thethrottle valve so that the idle channel is subjected to manifold vacuumat all times to provide normal idle and off idle speed vacuum signalswith corresponding mixture flow, an air bleed port in the idle channel,an electrically controlled valve movable to open and close the port, anelectrical circuit including an electrical source and electricallyactuated means connected to the valve, first means responsive to engineshutdown completing the circuit and energizing the electrically actuatedmeans to move the valve to open the port and decay the idle system fuelvacuum signal to terminate idle system fuel flow to prevent enginedieseling, and second means responsive to engine shutdown subsequent tooperation of the first means to break the circuit and de-energize theelectrically actuated means to effect movement of the valve to close theport, the second means comprising a spring opened, engine manifoldvacuum closed switch in the circuit between the source and first switch.

3. An engine anti-dieseling control comprising, in combination, anengine carburetor having an induction passage open to atmosphericpressure at one end and adapted to be connected to an engine intakemanifold at the opposite end so as to be subject to engine vacuumvarying in level from ambient atmospheric pressure at engine shutdown toa maximum subatmospheric pressure level during engine decelerationoperating conditions, a throttle valve rotatably mounted across thepassage and movable from a closed position to an engine idle speedposition and beyond to a wide open throttle position, and return, forcontrolling flow through the passage, an idle fuel/air mixture channelconnected to the induction passage below the closed position of thethrottle valve so that the idle channel is subjected to manifold vacuumat all times to provide normal idle and off idle speed vacuum signalswith corresponding mixture flow, an air bleed port in the idle channel,an electrically controlled valve movable to open and close the port, anelectrical circuit including an electrical source and electricallyactuated means connected to the valve, first means responsive to engineshutdown completing the circuit and energizing the electrically actuatedmeans to move the valve to open the port and decay the idle system fuelvacuum signal to terminate idle system fuel flow to prevent enginedieseling, and second means responsive to engine shutdown subsequent tooperation of the first means to break the circuit and de-engergize theelectrically actuated means to effect movement of the valve to close theport, the electrically actuated means comprising a solenoid having anarmature movable in one direction when energized and connected to thevalve, and spring means biasing the armature in a return direction, thefirst means comprising a relay controlled first switch in the circuitthat is spring closed to complete the circuit and opened to interruptthe circuit by energization of the relay, an engine ignition on-offswitch in the circuit between the source and relay interrupting thecircuit to the relay upon engine shutdown, the second means comprising asecond switch that is in a series circuit arrangement with the relaybetween the source and relay and in a parallel circuit arrangement withthe ignition switch, the second switch being spring opened and moved toa closed position by engine intake manifold vacuum applied theretoduring running operation of the engine, opening of the ignition switchupon shutdown of the engine effecting closing of the relay to completethe circuit and energizethe solenoid to open the air port, thesubsequent decay in manifold vacuum effecting opening of the secondswitch to break the circuit and de-energize the solenoid and effectclosing of the air port.

1. An engine anti-dieseling control comprising, in combination, anengine carburetor having an induction passage open to atmosphericpressure at one end and adapted to be connected to an engine intakemanifold at the opposite end so as to be subject to engine vacuumvarying in level from ambient atmospheric pressure at engine shutdown toa maximum subatmospheric pressure level during engine decelerationoperating conditions, a throttle valve rotatably mounted across thepassage and movable from a closed position to an engine idle speedposition and beyond to a wide open throttle position, and return, forcontrolling flow through the passage, an idle fuel/air mixture channelconnected to the inDuction passage below the closed position of thethrottle valve so that the idle channel is subjected to manifold vacuumat all times to provide normal idle and off idle speed vacuum signalswith corresponding mixture flow, an air bleed port in the idle channel,an electrically controlled valve movable to open and close the port, anelectrical circuit including an electrical source and electricallyactuated means connected to the valve, first means responsive to engineshutdown completing the circuit and energizing the electrically actuatedmeans to move the valve to open the port and decay the idle system fuelvacuum signal to terminate idle system fuel flow to prevent enginedieseling, and second means responsive to engine shutdown subsequent tooperation of the first means to break the circuit and de-energize theelectrically actuated means to effect movement of the valve to close theport, the first means including a spring closed first switch in thecircuit and a relay associated therewith energizable to open the switchand break the circuit, and an engine ignition on-off second switch in aseries circuit arrangement with the first switch between the source andswitch and in a parallel circuit arrangement with the second means. 2.An engine anti-dieseling control comprising, in combination, an enginecarburetor having an induction passage open to atmospheric pressure atone end and adapted to be connected to an engine intake manifold at theopposite end so as to be subject to engine vacuum varying in level fromambient atmospheric pressure at engine shutdown to a maximumsubatmospheric pressure level during engine deceleration operatingconditions, a throttle valve rotatably mounted across the passage andmovable from a closed position to an engine idle speed position andbeyond to a wide open throttle position, and return, for controllingflow through the passage, an idle fuel/air mixture channel connected tothe induction passage below the closed position of the throttle valve sothat the idle channel is subjected to manifold vacuum at all times toprovide normal idle and off idle speed vacuum signals with correspondingmixture flow, an air bleed port in the idle channel, an electricallycontrolled valve movable to open and close the port, an electricalcircuit including an electrical source and electrically actuated meansconnected to the valve, first means responsive to engine shutdowncompleting the circuit and energizing the electrically actuated means tomove the valve to open the port and decay the idle system fuel vacuumsignal to terminate idle system fuel flow to prevent engine dieseling,and second means responsive to engine shutdown subsequent to operationof the first means to break the circuit and de-energize the electricallyactuated means to effect movement of the valve to close the port, thesecond means comprising a spring opened, engine manifold vacuum closedswitch in the circuit between the source and first switch.
 3. An engineanti-dieseling control comprising, in combination, an engine carburetorhaving an induction passage open to atmospheric pressure at one end andadapted to be connected to an engine intake manifold at the opposite endso as to be subject to engine vacuum varying in level from ambientatmospheric pressure at engine shutdown to a maximum subatmosphericpressure level during engine deceleration operating conditions, athrottle valve rotatably mounted across the passage and movable from aclosed position to an engine idle speed position and beyond to a wideopen throttle position, and return, for controlling flow through thepassage, an idle fuel/air mixture channel connected to the inductionpassage below the closed position of the throttle valve so that the idlechannel is subjected to manifold vacuum at all times to provide normalidle and off idle speed vacuum signals with corresponding mixture flow,an air bleed port in the idle channel, an electrically controlled valvemovable to open and close the port, an electrical circuit including anelectrical source and electrically actuated means connected to thevalve, first means responsive to engine shutdown completing the circuitand energizing the electrically actuated means to move the valve to openthe port and decay the idle system fuel vacuum signal to terminate idlesystem fuel flow to prevent engine dieseling, and second meansresponsive to engine shutdown subsequent to operation of the first meansto break the circuit and de-engergize the electrically actuated means toeffect movement of the valve to close the port, the electricallyactuated means comprising a solenoid having an armature movable in onedirection when energized and connected to the valve, and spring meansbiasing the armature in a return direction, the first means comprising arelay controlled first switch in the circuit that is spring closed tocomplete the circuit and opened to interrupt the circuit by energizationof the relay, an engine ignition on-off switch in the circuit betweenthe source and relay interrupting the circuit to the relay upon engineshutdown, the second means comprising a second switch that is in aseries circuit arrangement with the relay between the source and relayand in a parallel circuit arrangement with the ignition switch, thesecond switch being spring opened and moved to a closed position byengine intake manifold vacuum applied thereto during running operationof the engine, opening of the ignition switch upon shutdown of theengine effecting closing of the relay to complete the circuit andenergize the solenoid to open the air port, the subsequent decay inmanifold vacuum effecting opening of the second switch to break thecircuit and de-energize the solenoid and effect closing of the air port.